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<pre><span class="sourceLineNo">001</span>/*<a name="line.1"></a>
<span class="sourceLineNo">002</span> * Licensed to the Apache Software Foundation (ASF) under one or more<a name="line.2"></a>
<span class="sourceLineNo">003</span> * contributor license agreements.  See the NOTICE file distributed with<a name="line.3"></a>
<span class="sourceLineNo">004</span> * this work for additional information regarding copyright ownership.<a name="line.4"></a>
<span class="sourceLineNo">005</span> * The ASF licenses this file to You under the Apache License, Version 2.0<a name="line.5"></a>
<span class="sourceLineNo">006</span> * (the "License"); you may not use this file except in compliance with<a name="line.6"></a>
<span class="sourceLineNo">007</span> * the License.  You may obtain a copy of the License at<a name="line.7"></a>
<span class="sourceLineNo">008</span> *<a name="line.8"></a>
<span class="sourceLineNo">009</span> *      http://www.apache.org/licenses/LICENSE-2.0<a name="line.9"></a>
<span class="sourceLineNo">010</span> *<a name="line.10"></a>
<span class="sourceLineNo">011</span> * Unless required by applicable law or agreed to in writing, software<a name="line.11"></a>
<span class="sourceLineNo">012</span> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.12"></a>
<span class="sourceLineNo">013</span> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.13"></a>
<span class="sourceLineNo">014</span> * See the License for the specific language governing permissions and<a name="line.14"></a>
<span class="sourceLineNo">015</span> * limitations under the License.<a name="line.15"></a>
<span class="sourceLineNo">016</span> */<a name="line.16"></a>
<span class="sourceLineNo">017</span>package org.apache.commons.io.input;<a name="line.17"></a>
<span class="sourceLineNo">018</span><a name="line.18"></a>
<span class="sourceLineNo">019</span>import java.io.IOException;<a name="line.19"></a>
<span class="sourceLineNo">020</span>import java.io.InputStream;<a name="line.20"></a>
<span class="sourceLineNo">021</span>import java.security.MessageDigest;<a name="line.21"></a>
<span class="sourceLineNo">022</span>import java.security.NoSuchAlgorithmException;<a name="line.22"></a>
<span class="sourceLineNo">023</span><a name="line.23"></a>
<span class="sourceLineNo">024</span><a name="line.24"></a>
<span class="sourceLineNo">025</span>/**<a name="line.25"></a>
<span class="sourceLineNo">026</span> * This class is an example for using an {@link ObservableInputStream}. It<a name="line.26"></a>
<span class="sourceLineNo">027</span> * creates its own {@link org.apache.commons.io.input.ObservableInputStream.Observer},<a name="line.27"></a>
<span class="sourceLineNo">028</span> * which calculates a checksum using a MessageDigest, for example an MD5 sum.<a name="line.28"></a>
<span class="sourceLineNo">029</span> * &lt;em&gt;Note&lt;/em&gt;: Neither {@link ObservableInputStream}, nor {@link MessageDigest},<a name="line.29"></a>
<span class="sourceLineNo">030</span> * are thread safe. So is {@link MessageDigestCalculatingInputStream}.<a name="line.30"></a>
<span class="sourceLineNo">031</span> */<a name="line.31"></a>
<span class="sourceLineNo">032</span>public class MessageDigestCalculatingInputStream extends ObservableInputStream {<a name="line.32"></a>
<span class="sourceLineNo">033</span><a name="line.33"></a>
<span class="sourceLineNo">034</span>    /**<a name="line.34"></a>
<span class="sourceLineNo">035</span>     * Maintains the message digest.<a name="line.35"></a>
<span class="sourceLineNo">036</span>     */<a name="line.36"></a>
<span class="sourceLineNo">037</span>    public static class MessageDigestMaintainingObserver extends Observer {<a name="line.37"></a>
<span class="sourceLineNo">038</span>        private final MessageDigest messageDigest;<a name="line.38"></a>
<span class="sourceLineNo">039</span><a name="line.39"></a>
<span class="sourceLineNo">040</span>        /**<a name="line.40"></a>
<span class="sourceLineNo">041</span>         * Creates an MessageDigestMaintainingObserver for the given MessageDigest.<a name="line.41"></a>
<span class="sourceLineNo">042</span>         * @param messageDigest the message digest to use<a name="line.42"></a>
<span class="sourceLineNo">043</span>         */<a name="line.43"></a>
<span class="sourceLineNo">044</span>        public MessageDigestMaintainingObserver(final MessageDigest messageDigest) {<a name="line.44"></a>
<span class="sourceLineNo">045</span>            this.messageDigest = messageDigest;<a name="line.45"></a>
<span class="sourceLineNo">046</span>        }<a name="line.46"></a>
<span class="sourceLineNo">047</span><a name="line.47"></a>
<span class="sourceLineNo">048</span>        @Override<a name="line.48"></a>
<span class="sourceLineNo">049</span>        public void data(final int input) throws IOException {<a name="line.49"></a>
<span class="sourceLineNo">050</span>            messageDigest.update((byte) input);<a name="line.50"></a>
<span class="sourceLineNo">051</span>        }<a name="line.51"></a>
<span class="sourceLineNo">052</span><a name="line.52"></a>
<span class="sourceLineNo">053</span>        @Override<a name="line.53"></a>
<span class="sourceLineNo">054</span>        public void data(final byte[] input, final int offset, final int length) throws IOException {<a name="line.54"></a>
<span class="sourceLineNo">055</span>            messageDigest.update(input, offset, length);<a name="line.55"></a>
<span class="sourceLineNo">056</span>        }<a name="line.56"></a>
<span class="sourceLineNo">057</span>    }<a name="line.57"></a>
<span class="sourceLineNo">058</span><a name="line.58"></a>
<span class="sourceLineNo">059</span>    private final MessageDigest messageDigest;<a name="line.59"></a>
<span class="sourceLineNo">060</span><a name="line.60"></a>
<span class="sourceLineNo">061</span>    /** Creates a new instance, which calculates a signature on the given stream,<a name="line.61"></a>
<span class="sourceLineNo">062</span>     * using the given {@link MessageDigest}.<a name="line.62"></a>
<span class="sourceLineNo">063</span>     * @param inputStream the stream to calculate the message digest for<a name="line.63"></a>
<span class="sourceLineNo">064</span>     * @param messageDigest the message digest to use<a name="line.64"></a>
<span class="sourceLineNo">065</span>     */<a name="line.65"></a>
<span class="sourceLineNo">066</span>    public MessageDigestCalculatingInputStream(final InputStream inputStream, final MessageDigest messageDigest) {<a name="line.66"></a>
<span class="sourceLineNo">067</span>        super(inputStream, new MessageDigestMaintainingObserver(messageDigest));<a name="line.67"></a>
<span class="sourceLineNo">068</span>        this.messageDigest = messageDigest;<a name="line.68"></a>
<span class="sourceLineNo">069</span>    }<a name="line.69"></a>
<span class="sourceLineNo">070</span><a name="line.70"></a>
<span class="sourceLineNo">071</span>    /**<a name="line.71"></a>
<span class="sourceLineNo">072</span>     * Creates a new instance, which calculates a signature on the given stream, using a {@link MessageDigest} with the<a name="line.72"></a>
<span class="sourceLineNo">073</span>     * given algorithm.<a name="line.73"></a>
<span class="sourceLineNo">074</span>     *<a name="line.74"></a>
<span class="sourceLineNo">075</span>     * @param inputStream the stream to calculate the message digest for<a name="line.75"></a>
<span class="sourceLineNo">076</span>     * @param algorithm the name of the algorithm to use<a name="line.76"></a>
<span class="sourceLineNo">077</span>     * @throws NoSuchAlgorithmException if no Provider supports a MessageDigestSpi implementation for the specified<a name="line.77"></a>
<span class="sourceLineNo">078</span>     *         algorithm.<a name="line.78"></a>
<span class="sourceLineNo">079</span>     */<a name="line.79"></a>
<span class="sourceLineNo">080</span>    public MessageDigestCalculatingInputStream(final InputStream inputStream, final String algorithm)<a name="line.80"></a>
<span class="sourceLineNo">081</span>        throws NoSuchAlgorithmException {<a name="line.81"></a>
<span class="sourceLineNo">082</span>        this(inputStream, MessageDigest.getInstance(algorithm));<a name="line.82"></a>
<span class="sourceLineNo">083</span>    }<a name="line.83"></a>
<span class="sourceLineNo">084</span><a name="line.84"></a>
<span class="sourceLineNo">085</span>    /**<a name="line.85"></a>
<span class="sourceLineNo">086</span>     * Creates a new instance, which calculates a signature on the given stream, using a {@link MessageDigest} with the<a name="line.86"></a>
<span class="sourceLineNo">087</span>     * "MD5" algorithm.<a name="line.87"></a>
<span class="sourceLineNo">088</span>     *<a name="line.88"></a>
<span class="sourceLineNo">089</span>     * @param inputStream the stream to calculate the message digest for<a name="line.89"></a>
<span class="sourceLineNo">090</span>     * @throws NoSuchAlgorithmException if no Provider supports a MessageDigestSpi implementation for the specified<a name="line.90"></a>
<span class="sourceLineNo">091</span>     *         algorithm.<a name="line.91"></a>
<span class="sourceLineNo">092</span>     */<a name="line.92"></a>
<span class="sourceLineNo">093</span>    public MessageDigestCalculatingInputStream(final InputStream inputStream) throws NoSuchAlgorithmException {<a name="line.93"></a>
<span class="sourceLineNo">094</span>        this(inputStream, MessageDigest.getInstance("MD5"));<a name="line.94"></a>
<span class="sourceLineNo">095</span>    }<a name="line.95"></a>
<span class="sourceLineNo">096</span><a name="line.96"></a>
<span class="sourceLineNo">097</span>    /** Returns the {@link MessageDigest}, which is being used for generating the<a name="line.97"></a>
<span class="sourceLineNo">098</span>     * checksum.<a name="line.98"></a>
<span class="sourceLineNo">099</span>     * &lt;em&gt;Note&lt;/em&gt;: The checksum will only reflect the data, which has been read so far.<a name="line.99"></a>
<span class="sourceLineNo">100</span>     * This is probably not, what you expect. Make sure, that the complete data has been<a name="line.100"></a>
<span class="sourceLineNo">101</span>     * read, if that is what you want. The easiest way to do so is by invoking<a name="line.101"></a>
<span class="sourceLineNo">102</span>     * {@link #consume()}.<a name="line.102"></a>
<span class="sourceLineNo">103</span>     * @return the message digest used<a name="line.103"></a>
<span class="sourceLineNo">104</span>     */<a name="line.104"></a>
<span class="sourceLineNo">105</span>    public MessageDigest getMessageDigest() {<a name="line.105"></a>
<span class="sourceLineNo">106</span>        return messageDigest;<a name="line.106"></a>
<span class="sourceLineNo">107</span>    }<a name="line.107"></a>
<span class="sourceLineNo">108</span>}<a name="line.108"></a>




























































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